Missing at interstate speed
 

Hey guys. I've got a 90 ranger with a 2.3/5 speed. when i got the truck, it would drop in rpm and lose power. i replaced both coils, plugs, wires, ignition module, IAT sensor, ECT sensor, EVP sensor,EGR valve, thermostat, and MAF sensor.I have also replaced many of the engine harness connectors that were broken or butt connected. all parts are factory ford and motorcraft. it does not lose power & drop in rpm anymore. the truck runs much better now, but still has a miss in it at around 65 to 75 miles an hour. if i downshift into 4th gear, it wont miss, but if i'm in 5th, it starts missing & hesitating. fuel pressure is fine.anyone have any ideas about what the hell is wrong with this damn thing?????

Im not sure, but after replacing all those parts what maybe happening is the valves are sticking in the valve guides. You need to pull the heads and ream the guides out and clean the valve stems. I would just send them out for a valve job as long as you had them off. OR it could be the gas your buying....